Digital Video Broadcasting (DVB) systems are being developed to agreed standards for the delivery of digital television and data services. Currently home users, for example, are receiving both analog and digital television broadcasts. IPTV is also available.
Within the home environment, users are distributing incoming broadcast programming such as TV services, and stored video content, and a home network may carry other content. As the uses to which networks are put increase, there may be conflict leading to overload of the network resources. Variations may occur in the ability of the network to transfer any specific stream of data reliably and consistently.
Actual network operating conditions need to provide a guaranteed throughput level, that is, there needs to be Quality of Service (QoS).
Of course, some activities can require much larger bandwidth than normal, a requirement which clearly leads to conflict with any other activities over the network. In the home environment, the network may have adequate capacity when only real time streams of content are being played. However, problems may arise from delivery scenarios which allow some of the content to be played in non real time, i.e. trick modes. When trick modes are added, the bit rate of an individual stream may increase several fold and at this point potentially all of the streams being delivered suffer.